import java.util.Scanner;

public class Main1305 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int a=sc.nextInt();
        int b=sc.nextInt();
        int c=sc.nextInt();
        int d=sc.nextInt();
        if (a>b){
            System.out.println(a);
        }else if (b>c){
            System.out.println(b);
        }else if (c>d){
            System.out.println(c);
        }else if (d>a){
            System.out.println(d);
        }


    }
}
